Paper detail

Glass shaping at nanoscale: Mechanical forming of brittle amorphous silica by engineered inelastic interaction of scanning electrons with matter

Amorphous silica deforms viscoplastically at elevated temperatures, as is common for brittle glasses. The key mechanism of viscoplastic deformation involves interatomic bond switching, which is known to be a thermally activated process. In this study, through systematic in-situ compression tests by scanning electron microscopy, the viscoplastic deformation of amorphous silica is observed without thermal activation. Furthermore, ductility does not increase monotonically with acceleration voltage and current density of the SEM e-beam but is maximized by a factor of three at a specific acceleration voltage and current density conditions (compared to beam-off conditions). A Monte Carlo simulation of the electron-matter interaction shows that the unique trends of viscoplastic deformation correlate with the interaction volume, i.e., the region within the material where inelastic electron scattering occurs. Changing the size of the migrating atomic clusters can lead to facility in rearrangements of the intramolecular bonds, hence leading to more sustained bond switching. Based on the interaction volume the mechanical shaping of small-scale amorphous silica structures under e-beam irradiation can be modeled with high-precision supporting the idea that this relatively low-voltage e-beam-irradiation induced viscoplastic-deformation technique holds great potential for advancing amorphous silica structure manufacturing and developing e-beam assisted manufacturing for covalently bonded non-metallic materials.